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# DataType [![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url] > Data type constructor.
## Installation ```bash npm install @stdlib/ndarray-dtype-ctor ```
## Usage ```javascript var DataType = require( '@stdlib/ndarray-dtype-ctor' ); ``` #### DataType( value\[, options] ) Returns a data type instance. ```javascript var dt = new DataType( 'float64' ); // returns ``` The constructor supports the following parameters: - **value**: data type value. Must be either a supported [data type][@stdlib/ndarray/dtypes] string, a [struct][@stdlib/dstructs/struct] constructor, or another data type instance. - **options**: constructor options (_optional_). The constructor supports the following options: - **description**: data type description. * * * ## Properties #### DataType.prototype.alignment Alignment (in bytes) for the data type. ```javascript var dt = new DataType( 'float64' ); // returns var v = dt.alignment; // returns 8 ``` If a data type does not have a known alignment, the returned value is `-1`. #### DataType.prototype.byteLength Size (in bytes) for the data type. ```javascript var dt = new DataType( 'float64' ); // returns var v = dt.byteLength; // returns 8 ``` If a data type does not have a known size, the returned value is `-1`. #### DataType.prototype.byteOrder Data type byte order. ```javascript var dt = new DataType( 'float64' ); // returns var v = dt.byteOrder; // returns 'host' ``` The byte order may be one of the following values: - **host**: host platform byte order. - **little-endian**: little-endian byte order. - **big-endian**: big-endian byte order. #### DataType.prototype.char Single letter character abbreviation for the data type. ```javascript var dt = new DataType( 'float64' ); // returns var v = dt.char; // returns 'd' ``` If a data type does not have a corresponding single letter character abbreviation, the returned value is an empty string. #### DataType.prototype.description Data type description. ```javascript var dt = new DataType( 'float64' ); // returns var v = dt.description; // returns '...' ``` If a data type does not have an associated description, the returned value is an empty string. #### DataType.prototype.enum Enumeration constant for the data type. ```javascript var dt = new DataType( 'float64' ); // returns var v = dt.enum; // returns ``` If a data type does not have a corresponding known enumeration constant, the returned value is `-1`. **Note**: enumeration constants should be treated as **opaque** values. One should **not** assume that a data type has a specific enumeration constant value. #### DataType.prototype.value Raw (original) data type value. ```javascript var dt = new DataType( 'float64' ); // returns var v = dt.value; // returns 'float64' ``` * * * ## Methods #### DataType.prototype.toJSON() Returns a [JSON][json] representation of a `DataType` instance. ```javascript var dt = new DataType( 'float64' ); // returns var o = dt.toJSON(); // e.g., returns { 'type': 'DataType', 'value': 'float64', 'byteOrder': 'host', ... } ``` [`JSON.stringify()`][mdn-json-stringify] implicitly calls this method when stringifying a `DataType` instance. #### DataType.prototype.toString() Returns a string representation of a `DataType` instance. ```javascript var dt = new DataType( 'float64' ); // returns var str = dt.toString(); // returns 'float64' ``` #### DataType.prototype.valueOf() Converts a `DataType` instance to a primitive value. ```javascript var dt = new DataType( 'float64' ); // returns var str = dt.valueOf(); // returns 'float64' ``` This method returns the same value as `#.toString()`.
* * *
## Examples ```javascript var DataType = require( '@stdlib/ndarray-dtype-ctor' ); var dt = new DataType( 'complex128' ); console.log( 'type: %s', typeof dt ); // => 'type: object' console.log( 'alignment: %d', dt.alignment ); // => 'alignment: 8' console.log( 'byteLength: %d', dt.byteLength ); // => 'byteLength: 16' console.log( 'byteOrder: %s', dt.byteOrder ); // => 'byteOrder: host' console.log( 'char: %s', dt.char ); // => 'char: z' console.log( 'JSON: %s', JSON.stringify( dt ) ); // e.g., => 'JSON: {"type": "DataType","value":"complex128","byteOrder":"host",...}' ```
* * * ## See Also - [`@stdlib/ndarray-ctor`][@stdlib/ndarray/ctor]: multidimensional array constructor. - [`@stdlib/ndarray-dtype`][@stdlib/ndarray/dtype]: return the data type of a provided ndarray.
* * * ## Notice This package is part of [stdlib][stdlib], a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more. For more information on the project, filing bug reports and feature requests, and guidance on how to develop [stdlib][stdlib], see the main project [repository][stdlib]. #### Community [![Chat][chat-image]][chat-url] --- ## License See [LICENSE][stdlib-license]. ## Copyright Copyright © 2016-2026. The Stdlib [Authors][stdlib-authors].
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